Abstract
This study was conducted to examine the effects of a diet formulated with industrial amino acids and a commercial vitamin-mineral mixture on the characteristics of carcass and meat cuts of slow-growing broilers slaughtered at different ages. The experiment involved 600 one-day-old male and female white Naked Neck chicks. The chicks were allotted randomly to a 2 × 3 factorial arrangement consisting of two diets and three slaughter ages, in a completely randomized experimental design with five replicates of 20 birds each. The experimental period was 84 days. Six chicks were selected and slaughtered on the first day, and then at 56, 70 and 84 days of age 10 birds unit was selected and slaughtered per experimental period. Weight and yield of carcass, abdominal fat and breast, thigh and drumstick meat were determined. Additionally, moisture, protein, fat and mineral matter contents and protein and fat deposition in the breast, drumstick and thigh muscles were determined. The diet did not influence the yields of carcass, abdominal fat, or meat cuts or the nutritional composition of meat. Slaughter age influenced the yields of breast and thigh meat and abdominal fat; the protein content of breast meat; and the moisture, crude protein, fat, and mineral matter contents of drumstick and thigh meat. There was an interaction effect between diet and slaughter age for protein deposition in breast meat. The age factor influenced fat deposition in the drumstick muscles. Protein deposition in the thigh muscles was influenced by the diet. Moreover, a difference was observed between the ages for protein and fat deposition in the thigh muscle. In conclusion, the use of a commercial mixture in the diet results in decreased protein deposition in the breast and thigh muscles, although this difference does not affect the characteristics of carcass or meat cuts. Birds slaughtered at 70 days exhibit similar carcass characteristics to those of birds slaughtered at 84 days, indicating the possibility of an earlier slaughter age.
Key words
carcass yield; naked neck; nutritional composition; slaughter age